21969679 has 4 divisors (see below), whose sum is σ = 21984040. Its totient is φ = 21955320.

The previous prime is 21969677. The next prime is 21969691. The reversal of 21969679 is 97696912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21969679 - 2¹ = 21969677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21969671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4569 + ... + 8050.

It is an arithmetic number, because the mean of its divisors is an integer number (5496010).

Almost surely, 2^21969679 is an apocalyptic number.

21969679 is a deficient number, since it is larger than the sum of its proper divisors (14361).

21969679 is a wasteful number, since it uses less digits than its factorization.

21969679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14360.

The product of its digits is 367416, while the sum is 49.

The square root of 21969679 is about 4687.1824159083. The cubic root of 21969679 is about 280.0751456471.

The spelling of 21969679 in words is "twenty-one million, nine hundred sixty-nine thousand, six hundred seventy-nine".